The present invention relates to the transmission method of the driving signal of a liquid crystal display apparatus.
Recently, a technology has been developed for use on a display apparatus, configured by a liquid crystal panel and a backlight, where LEDs (Light-Emitting Diode) are used on the backlight. An LED that reflects or guides light can be used as a surface light emitter of any shape and, due to its steep emission spectrum, can reproduce high-saturation colors. Another advantage is a high-speed driving control ability that allows the backlight brightness to be adjusted with the display on the liquid crystal panel.
A technology for controlling both video signals and the light source brightness is disclosed in Japanese Patent No. 3430998. For use on a liquid crystal display, this patent discloses an apparatus configuration and a method in which, with signal amplitude control unit and light source control unit, the video signals and light source brightness are controlled to maintain the average brightness for improving the contrast.
The apparatus further comprises a unit for calculating the maximum value, minimum value, and average value in a frame of received image data and a unit for measuring a change in the signals between frames in order to reduce the deterioration of signals such as flickering.
The technology disclosed in Japanese Patent No. 3430998 measures the maximum value and the minimum value of the signals in a screen, calculates the gain and the offset, and corrects the amplitude range of the input signals to use the signals as display data and to adjust the brightness of the backlight of the liquid crystal display. To do so, it is necessary to detect the maximum value and the minimum value of the signals in the screen. According to the processing procedure of the disclosed technology, all signals in a screen must be received to give the measurement result. One of the problems with the technology disclosed in Japanese Patent No. 3430998 is that the time at which the signals are measured in a screen, the time at which the signals are corrected based on the measured result, and the time at which the corrected result is output are not well synchronized. In the configuration of the apparatus shown by the drawings and the description, the screen in which the signals are measured is not the screen in which the measurement result is reflected. Because a moving image signal in the screen varies from frame to frame, the dynamic range correction according to the prior art disclosed in Japanese Patent No. 3430998 is inconsistent in principle.